Hydrography Midterm Reviewer

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Hydrography Midterm Reviewer

  1. 1. Hydrographic Survey<br />Ildefonso, Sorbi<br />
  2. 2. Hydrography<br /><ul><li>Branch of science that deals with the measurement of bodies of water
  3. 3. Deals with the physical features of the navigable portion of the earth’s surface and adjoining coastal areas.
  4. 4. Sounding –measurement of depth below the water surface
  5. 5. Applications of sounding:
  6. 6. Making nautical charts for safety of navigation
  7. 7. Development and engineering projects such as piers, dams and bridges
  8. 8. Scientific and academic studies</li></li></ul><li>Horizontal Control and Vertical Control<br /><ul><li>Horizontal Control
  9. 9. For large areas – 2nd or 3rd order triangulation
  10. 10. For smaller areas – transit-tape traverse
  11. 11. For small detached areas – stadia, graphical, plane table methods
  12. 12. For long narrow river – traverse on one side
  13. 13. For width >1km – traverse on both sides
  14. 14. Vertical Control
  15. 15. Tide gauges are used to establish the common datum before sounding is taken</li></li></ul><li>Shoreline Survey<br /><ul><li>Shoreline
  16. 16. Syn. to Coastline
  17. 17. Line of contact between the land and the body of water
  18. 18. USC&GS uses the high water line
  19. 19. It consist of:
  20. 20. Determination or delineation of shorelines
  21. 21. Location of shore details and prominent features to which soundings may be connected
  22. 22. Determination of low and high water lines</li></li></ul><li>Methods of Locating Sounding<br /><ul><li>From the shore
  23. 23. Location by Cross-Rope
  24. 24. Location by two angles from the shore
  25. 25. Location by Range and One angle from the shore
  26. 26. From the boat
  27. 27. Location by two angle from the boat
  28. 28. Location by Range and One angle from the boat
  29. 29. From both the shore and the boat
  30. 30. Location by One angle from the shore and from the boat
  31. 31. Location by Range and Time Intervals of the boat
  32. 32. Location by Intersecting Ranges
  33. 33. Location by Tacheometric Observations</li></li></ul><li>Sounding Lines<br /><ul><li>Systems of Sounding Lines
  34. 34. Parallel straight lines –> open coasts
  35. 35. Radiating lines –> small bays and islets
  36. 36. Circular curves or arcs –> isolated shoal
  37. 37. Spacing of Sounding Lines
  38. 38. Factors: the scale of the survey, depth of water, proximity to shore, character of submarine relief, importance of the region</li></li></ul><li>Instruments used in Sounding<br /><ul><li>The methods of determining water depth are differentiated by the instruments used .
  39. 39. Sounding Pole
  40. 40. The Leadline
  41. 41. Sounding Machines
  42. 42. Registering sheaves
  43. 43. Echo sounding Instrument or Fathometer</li></li></ul><li>Echo Sounding<br />Distance is measured by multiplying half the time(t) from the signal's outgoing pulse to its return by the speed of sound(S) in the water, which is approximately 1.5 kilometres per second.<br />D=0.5(t)*S<br />It takes in to account the factors of temperature, pressure and salinity to calculate the actual sound speed.<br />
  44. 44. Reduction of Sounding<br />The reduced sounding are the reduced levels of the submarine surface in terms of the adopted datum<br />A correction equal to the difference of level between the actual water level(gauge reading) and the datum(MLW/MLLW) is applied to the observed soundings.<br />
  45. 45. Hydrographic Survey Team<br />Officer-in-charge/Chief-of-party<br />Left Angleman<br />Right Angleman<br />Recorder<br />Fathometer attendant<br />Leadsman<br />Leadsman’s assistant<br />Helmsman or Coxwain<br />Engineer<br />Additional general utility personnel<br />
  46. 46. Hydrography and Cartography<br /><ul><li>Cartography – science and art of the production of maps and charts
  47. 47. Nautical charts-> polyconic projection
  48. 48. Instruments used in the preparation of Nautical Charts
  49. 49. 3-arm protractor
  50. 50. Hairspring divider
  51. 51. Spacing divider
  52. 52. Proportional divider
  53. 53. Meter Bar
  54. 54. Opisometer/Map measure
  55. 55. Beam Compass</li></li></ul><li>The Nautical Chart<br /><ul><li>A nautical chart is a graphic representation of a maritime area and adjacent coastal regions.
  56. 56. Datums of a Nautical Chart
  57. 57. Horizontal Datum
  58. 58. Vertical Datum
  59. 59. Atlantic Ocean – Mean Low Water
  60. 60. Pacific Ocean – Mean Lower Low Water</li></li></ul><li>Nautical Chart<br /><ul><li>The Nautical chart or hydrographic map should contain the following information
  61. 61. Datum used
  62. 62. High, mean, low water lines
  63. 63. Soundings
  64. 64. Line of equal interpolated from the soundings called depth curves
  65. 65. Conventional symbols
  66. 66. All safety devices such as lighthouse, buoys etc.
  67. 67. Complete border information</li></li></ul><li>Plotting of Soundings<br /><ul><li>Soundings can be plotted in 3 ways
  68. 68. Mechanical Solution
  69. 69. By tracing paper
  70. 70. By Station Pointer
  71. 71. Graphical Solution
  72. 72. Method 1
  73. 73. Method 2
  74. 74. Analytical Solution</li></li></ul><li>Other Essential in Hydrography<br />The Sextant<br />An instrument used to measure the angle between any two visible objects. <br />The Boat sheet/Hydrographic sheet<br />The Wire drag<br />A device used to detect obstructions such as boulders and ledges. These obstructions should be plotted in the Navigational charts.<br />
  75. 75. Common Terms used in Hydrography<br />Marginal continental features<br />Bank<br />Continental shelf<br />Continental slope<br />Insular shelf<br />Insular slope<br />Deep Sea Depression <br />& Deep Sea Elevations<br />Basin<br />Deep<br />Depression<br />Depth<br />Foredeep<br />Trench<br />Plateadu<br />Ridge<br />Seamount<br />Swell<br />
  76. 76. Common Terms used in Hydrography<br />Embayments<br />Bay<br />Bright<br />Cove<br />Harbor<br />Inlet<br />Gulf<br />Coastal Features<br />Cape<br />Coast<br />High-water Line<br />Island<br />Islet<br />Low-water line<br />Point<br />
  77. 77. Common Terms used in Hydrography<br />Streams<br />Bayou<br />Brook and Run<br />Creek<br />Lagoon<br />River<br />Slough<br />Caldron<br />Canyon<br />Seavalley<br />Valley<br />Submarine Elevations<br />Bank<br />Crest<br />Dome Knoll<br />Ledge<br />Pinnacle<br />Reef<br />Shoal<br />Spur<br />

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